nt secondary err code: 238

[Liggs]

We are getting a strange problem with our Oracle 8i 8.1.7.4 listeners (which we didn't have on our old Oracle 7 listeners).
[We just upgraded to 8i].
Basically all works fine until early in the morning when SOME connections fail for about an hour.
sqlnet.log says :-
TNS-12535: TNS:operation timed out
ns secondary err code: 12560
nt main err code: 505
TNS-00505: Operation timed out
nt secondary err code: 238
nt OS err code: 0
nt secondary err code: 238
nt OS err code: 0
nt secondary err code: 238

We've put the CONNECT_TIMEOUT up in the listener.ora to 20 seconds. But after I started to quiz Oracle about the "nt secondary err code: 238" they said it was a HP OS error message and I should find out what it means.

Any ideas what error 238 is?? Something to do with network timeout???

Thanks.

[RAC_1]

Error code 238 is time out error. what port the listener is listening to?

(mostly 1521)

May be the time out is happening on that port.

Seems that there are lot of connections happenning on 1521 in the morning.

Check tcp_timeout value set.